1. Field of the Invention
The present invention relates to a valve guide structure used in a pressurized fluid control device, such as a pressure reduction valve or the like, and more specifically concerns a valve guide structure for preventing damage to a resin manufactured valve guide.
2. Description of the Related Art
There has hitherto been used a valve guide structure in a pressurized fluid control device, such as a pressure reduction valve or the like. A pressure reduction valve 10 using such a valve guide structure is shown in FIG. 13. The pressure reduction valve 10 includes a main body 18 having a first side port 12 and a second side port 14 defined therein, a bonnet 22 which is fitted to an upper part of the main body 18, and a handle 24 rotatably supported about an axis on an upper part of the bonnet 22.
A recess 26 is defined in a lower part of the main body 18, wherein a circumferential groove 27 is defined around a wall formed in the recess 26. A valve guide body 30 is formed by a resin in order to reduce frictional resistance of the valve body 34, which is slidably inserted into a cavity 32 of the valve guide body 30, and to prevent sticking of the valve body 34. A plurality of hooks 38, which are separated mutually by plural slits 35, are formed in the valve guide body 30, wherein by engagement of the hooks 38 with a wall formed by the groove 27, the valve guide body 30 is stopped from falling out of the recess 26. The valve body 34 is supported by a coil spring 36. A rod-shaped stem 40 is affixed to an upper-central portion of the valve body 34, wherein an end of the stem 40 is formed to have an upwardly tapering reduced diameter.
A chamber 42, through which the stem 40 penetrates and which communicates with the second side port 14, is formed in the main body 18. A seat 44 capable of abutment with an upper surface of the valve body 34 is formed on a lower part of a substantially cylindrically shaped wall of the chamber 42.
A diaphragm 46 extends between the main body 18 and the bonnet 22, wherein a diaphragm chamber 48 is formed by the diaphragm 46 and a recess in the main body 18. A diaphragm pressing member 52 is disposed centrally on the diaphragm 46, wherein a through hole 56 is defined in the center of the diaphragm pressing member 52. A radially downward extending taper 58 is formed by a wall of the through hole 56, wherein an end of the stem abuts inside the taper 58, thereby blocking the through hole 56.
A seat 54 is disposed on top of the diaphragm 46 on the diaphragm pressing member 52, and a pressure adjustment spring 50 is seated on the seat 54, wherein the other end of the pressure adjustment spring 60 engages a pressure adjusting nut 62. The pressure adjusting nut 62 threadedly engages a pressure adjusting screw 64 affixed to the handle 24, so that by turning the handle 24, the pressure adjusting nut 62 is displaced in directions of arrows A and B.
Further, in a valve guide structure 80 according to another conventional technique, as shown in FIG. 14, a large diameter hole 82 communicates with a lower part of a recess 26 of a valve body 18, wherein a plurality of projections 84 are formed along a wall of the recess 82. By contrast, on an outer circumference of the valve guide body 86, projections 88 are formed which are engageable with the projections 84, wherein following insertion of the valve guide body 86 into the hole 26 in a manner such that the projections 88 do not abut with the projections 84 of the recess 82, the valve guide body 86 is rotated a predetermined angle in a circumferential direction thereof, so that the projections 88 of the valve guide body 86 and the projections 84 of the hole 82 engage one another for stopping the valve guide body 86 from falling out.
Further, a valve guide structure 90 according to yet another conventional technique, as shown in FIG. 15, is defined by a groove 92 which surrounds a wall formed by a recess 26 of a main valve body 18, wherein through engagement of a C-shaped stop ring 94 in the groove 92, the valve guide body 96 is prevented from falling out.
Notwithstanding, with the valve guide structures 28, 80, 90 of these conventional techniques, because the valve guide bodies 30, 86, 96 are formed of a resin, when the valve guide structures 28, 80, 90 are subjected to pressure from a pressurized fluid, there is a concern that a corresponding force is concentrated on the valve guide bodies 30, 86, 96, wherein damage to the valve guide bodies 30, 86, 90 can result.
Further, there is a concern of deterioration from changes occurring to the valve guide bodies 30, 86, 96 over time, with the defect that damage to the valve guide body 30, 86, 96 becomes easy due to use thereof over prolonged periods.
Furthermore, although attachment of such valve guide structures 28, 80, 90 is easy, at the same time, there is the concern that the valve guide bodies 30, 86, 96 may unexpectedly become dislocated by becoming loosened or the like.